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Sagués Carracedo, AnaORCID iD iconorcid.org/0000-0002-3498-2167
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Publications (10 of 24) Show all publications
Sagués Carracedo, A. (2024). Chasing Cosmic Rarities: Kilonovae and Gravitationally Lensed Supernovae in Optical Surveys. (Doctoral dissertation). Stockholm: Department of Physics, Stockholm University
Open this publication in new window or tab >>Chasing Cosmic Rarities: Kilonovae and Gravitationally Lensed Supernovae in Optical Surveys
2024 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on two important topics in astrophysics: the detection of kilonovae (KNe) and gravitationally lensed supernovae (glSNe) in optical surveys. In the first part, the study quantifies the impact of survey depth and choice of filters on the detection probability of KNe. The results highlight the importance of accounting for asymmetries expected for KNe, and despite several search campaigns, no KNe were detected by the Zwicky Transient Facility (ZTF). Nonetheless, non-detection studies provided meaningful constraints on the luminosity function and on the rates of KNe. The findings contribute to advancing our understanding of these rare, fast, and faint transients. I also discuss the improvements in measuring the Hubble constant with follow-up data of KNe, including broadband photometry and spectrophotometric data from the upcoming IFU instrument MAAT. 

The second part of the thesis focuses on gravitationally lensed supernovae. The ZTF survey was expected to detect more than one strongly lensed supernova per year, but only one was identified in the first five years. The study presents simulations of lightcurves for lensed supernovae and new rates based on realistic survey simulations for ZTF. Optimal cuts to distinguish lensed supernovae from normal unlensed supernovae are also provided. The thesis discusses time delay and lightcurve modeling for the one event found during ZTF, SN Zwicky, and the lessons learned from it.

The techniques developed in this thesis can be applied to future surveys to increase the detection rate of KNe and glSNe. These events and their underlying physics provide valuable insights in cosmology.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2024. p. 80
Keywords
supernova, strong gravitational lensing, kilonova, gravitational waves, optical surveys
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-228303 (URN)978-91-8014-765-1 (ISBN)978-91-8014-766-8 (ISBN)
Public defence
2024-05-30, lärosal 4, hus 1, Albano, Albanovägen 28, Stockholm, 13:00 (English)
Opponent
Supervisors
Available from: 2024-05-06 Created: 2024-04-11 Last updated: 2024-04-25Bibliographically approved
Goobar, A., Pearson Johansson, J., Schulze, S., Arendse, N., Sagués Carracedo, A., Dhawan, S., . . . Wold, A. (2023). Uncovering a population of gravitational lens galaxies with magnified standard candle SN Zwicky. Nature Astronomy, 7(9), 1098-1107
Open this publication in new window or tab >>Uncovering a population of gravitational lens galaxies with magnified standard candle SN Zwicky
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2023 (English)In: Nature Astronomy, E-ISSN 2397-3366, Vol. 7, no 9, p. 1098-1107Article in journal (Refereed) Published
Abstract [en]

Detecting gravitationally lensed supernovae is among the biggest challenges in astronomy. It involves a combination of two very rare phenomena: catching the transient signal of a stellar explosion in a distant galaxy and observing it through a nearly perfectly aligned foreground galaxy that deflects light towards the observer. Here we describe how high-cadence optical observations with the Zwicky Transient Facility, with its unparalleled large field of view, led to the detection of a multiply imaged type Ia supernova, SN Zwicky, also known as SN 2022qmx. Magnified nearly 25-fold, the system was found thanks to the standard candle nature of type Ia supernovae. High-spatial-resolution imaging with the Keck telescope resolved four images of the supernova with very small angular separation, corresponding to an Einstein radius of only θE = 0.167″ and almost identical arrival times. The small θE and faintness of the lensing galaxy are very unusual, highlighting the importance of supernovae to fully characterize the properties of galaxy-scale gravitational lenses, including the impact of galaxy substructures.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-228293 (URN)10.1038/s41550-023-01981-3 (DOI)001007443400006 ()2-s2.0-85161680486 (Scopus ID)
Note

For correction, see: Goobar, A., Johansson, J., Schulze, S. et al. Author Correction: Uncovering a population of gravitational lens galaxies with magnified standard candle SN Zwicky. Nat Astron 7, 1137 (2023). DOI: 10.1038/s41550-023-02034-5

Available from: 2024-04-11 Created: 2024-04-11 Last updated: 2024-04-12Bibliographically approved
Andreoni, I., Sagués Carracedo, A., Schulze, S., Sollerman, J., Bulla, M., Kool, E. C. & Zhang, J. (2022). A very luminous jet from the disruption of a star by a massive black hole. Nature, 612(7940), 430-434
Open this publication in new window or tab >>A very luminous jet from the disruption of a star by a massive black hole
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2022 (English)In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 612, no 7940, p. 430-434Article in journal (Refereed) Published
Abstract [en]

Tidal disruption events (TDEs) are bursts of electromagnetic energy that are released when supermassive black holes at the centres of galaxies violently disrupt a star that passes too close1. TDEs provide a window through which to study accretion onto supermassive black holes; in some rare cases, this accretion leads to launching of a relativistic jet2,3,4,5,6,7,8,9, but the necessary conditions are not fully understood. The best-studied jetted TDE so far is Swift J1644+57, which was discovered in γ-rays, but was too obscured by dust to be seen at optical wavelengths. Here we report the optical detection of AT2022cmc, a rapidly fading source at cosmological distance (redshift z = 1.19325) the unique light curve of which transitioned into a luminous plateau within days. Observations of a bright counterpart at other wavelengths, including X-ray, submillimetre and radio, supports the interpretation of AT2022cmc as a jetted TDE containing a synchrotron ‘afterglow’, probably launched by a supermassive black hole with spin greater than approximately 0.3. Using four years of Zwicky Transient Facility10 survey data, we calculate a rate of 0.02+0.04−0.01 Gpc−3 yr−1 for on-axis jetted TDEs on the basis of the luminous, fast-fading red component, thus providing a measurement complementary to the rates derived from X-ray and radio observations11. Correcting for the beaming angle effects, this rate confirms that approximately 1 per cent of TDEs have relativistic jets. Optical surveys can use AT2022cmc as a prototype to unveil a population of jetted TDEs.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-215888 (URN)10.1038/s41586-022-05465-8 (DOI)000936400900029 ()36450988 (PubMedID)2-s2.0-85143175488 (Scopus ID)
Available from: 2023-03-30 Created: 2023-03-30 Last updated: 2024-05-30Bibliographically approved
Pérez-García, M. A., Izzo, L., Barba-González, D., Bulla, M., Sagués-Carracedo, A., Pérez, E., . . . Sollerman, J. (2022). Hubble constant and nuclear equation of state from kilonova spectro-photometric light curves. Astronomy and Astrophysics, 666, Article ID A67.
Open this publication in new window or tab >>Hubble constant and nuclear equation of state from kilonova spectro-photometric light curves
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2022 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 666, article id A67Article in journal (Refereed) Published
Abstract [en]

The merger of two compact objects of which at least one is a neutron star is signalled by transient electromagnetic emission in a kilonova (KN). This event is accompanied by gravitational waves and possibly other radiation messengers such as neutrinos or cosmic rays. The electromagnetic emission arises from the radioactive decay of heavy r-process elements synthesized in the material ejected during and after the merger. In this paper we show that the analysis of KNe light curves can provide cosmological distance measurements and constrain the properties of the ejecta. In this respect, MAAT, the new Integral Field Unit in the OSIRIS spectrograph on the 10.4 m Gran Telescopio CANARIAS (GTC), is well suited for the study of KNe by performing absolute spectro-photometry over the entire 3600 − 10 000 Å spectral range. Here, we study the most representative cases regarding the scientific interest of KNe from binary neutron stars, and we evaluate the observational prospects and performance of MAAT on the GTC to do the following: (a) study the impact of the equation of state on the KN light curve, and determine to what extent bounds on neutron star (NS) radii or compactness deriving from KN peak magnitudes can be identified and (b) measure the Hubble constant, H0, with precision improved by up to 40%, when both gravitational wave data and photometric-light curves are used. In this context we discuss how the equation of state, the viewing angle, and the distance affect the precision and estimated value of H0.

Keywords
radiative transfer, stars: neutron, cosmological parameters, gravitational waves, equation of state
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-210734 (URN)10.1051/0004-6361/202243749 (DOI)000864854000007 ()
Available from: 2022-10-26 Created: 2022-10-26 Last updated: 2024-04-11Bibliographically approved
Ahumada, T., Anand, S., Coughlin, M. W., Andreoni, I., Kool, E. C., Kumar, H., . . . Roberts, O. (2022). In Search of Short Gamma-Ray Burst Optical Counterparts with the Zwicky Transient Facility. Astrophysical Journal, 932(1), Article ID 40.
Open this publication in new window or tab >>In Search of Short Gamma-Ray Burst Optical Counterparts with the Zwicky Transient Facility
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2022 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 932, no 1, article id 40Article in journal (Refereed) Published
Abstract [en]

The Fermi Gamma-ray Burst Monitor (GBM) triggers on-board in response to ∼40 short gamma-ray bursts (SGRBs) per year; however, their large localization regions have made the search for optical counterparts a challenging endeavour. We have developed and executed an extensive program with the wide field of view of the Zwicky Transient Facility (ZTF) camera, mounted on the Palomar 48 inch Oschin telescope (P48), to perform target-of-opportunity (ToO) observations on 10 Fermi-GBM SGRBs during 2018 and 2020–2021. Bridging the large sky areas with small field-of-view optical telescopes in order to track the evolution of potential candidates, we look for the elusive SGRB afterglows and kilonovae (KNe) associated with these high-energy events. No counterpart has yet been found, even though more than 10 ground-based telescopes, part of the Global Relay of Observatories Watching Transients Happen (GROWTH) network, have taken part in these efforts. The candidate selection procedure and the follow-up strategy have shown that ZTF is an efficient instrument for searching for poorly localized SGRBs, retrieving a reasonable number of candidates to follow up and showing promising capabilities as the community approaches the multi-messenger era. Based on the median limiting magnitude of ZTF, our searches would have been able to retrieve a GW170817-like event up to ∼200 Mpc and SGRB afterglows to z = 0.16 or 0.4, depending on the assumed underlying energy model. Future ToOs will expand the horizon to z = 0.2 and 0.7, respectively.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-207103 (URN)10.3847/1538-4357/ac6c29 (DOI)000810734100001 ()
Available from: 2022-07-07 Created: 2022-07-07 Last updated: 2022-07-07Bibliographically approved
Mohite, S. R., Rajkumar, P., Anand, S., Kaplan, D. L., Coughlin, M. W., Sagués Carracedo, A., . . . Singer, L. P. (2022). Inferring Kilonova Population Properties with a Hierarchical Bayesian Framework. I. Nondetection Methodology and Single-event Analyses. Astrophysical Journal, 925(1), Article ID 58.
Open this publication in new window or tab >>Inferring Kilonova Population Properties with a Hierarchical Bayesian Framework. I. Nondetection Methodology and Single-event Analyses
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2022 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 925, no 1, article id 58Article in journal (Refereed) Published
Abstract [en]

We present nimbus: a hierarchical Bayesian framework to infer the intrinsic luminosity parameters of kilonovae (KNe) associated with gravitational-wave (GW) events, based purely on nondetections. This framework makes use of GW 3D distance information and electromagnetic upper limits from multiple surveys for multiple events and self-consistently accounts for the finite sky coverage and probability of astrophysical origin. The framework is agnostic to the brightness evolution assumed and can account for multiple electromagnetic passbands simultaneously. Our analyses highlight the importance of accounting for model selection effects, especially in the context of nondetections. We show our methodology using a simple, two-parameter linear brightness model, taking the follow-up of GW190425 with the Zwicky Transient Facility as a single-event test case for two different prior choices of model parameters: (i) uniform/uninformative priors and (ii) astrophysical priors based on surrogate models of Monte Carlo radiative-transfer simulations of KNe. We present results under the assumption that the KN is within the searched region to demonstrate functionality and the importance of prior choice. Our results show consistency with simsurvey-an astronomical survey simulation tool used previously in the literature to constrain the population of KNe. While our results based on uniform priors strongly constrain the parameter space, those based on astrophysical priors are largely uninformative, highlighting the need for deeper constraints. Future studies with multiple events having electromagnetic follow-up from multiple surveys should make it possible to constrain the KN population further.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-201930 (URN)10.3847/1538-4357/ac3981 (DOI)000746691400001 ()
Available from: 2022-02-10 Created: 2022-02-10 Last updated: 2022-02-25Bibliographically approved
Sagués Carracedo, A. (2022). Kilonova signatures and observations with Zwicky Transient Facility. (Licentiate dissertation). Stockholm University
Open this publication in new window or tab >>Kilonova signatures and observations with Zwicky Transient Facility
2022 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

On 17 August 2017, the advanced LIGO and Virgo collaboration detected the first gravitational wave event produced by the merger of a pair of inspiraling binary neutron stars (BNS). This event, named GW170817, was associated with a short gamma-ray burst and the kilonova (KN) AT2017gfo that was followed-up over the following days and weeks over the electromagnetic spectrum from ultraviolet to near infrared frequencies. The merger was localized in a nearby galaxy, NGC 4993 at a distance of 40 Mpc. The close proximity and the orientation of the merger was favourable for studying its properties and evolution with time. 

This unique discovery gave rise to a new era in multimessenger astronomy and showed the relevance of these events in astrophysics, cosmology, and nuclear physics. Today, we aim at detecting samples of kilonovae to answer the many open questions related to BNS mergers and their use as physics laboratories. However, the observations of kilonovae are generally challenging as these are rare, fast and faint transients.

In this licentiate thesis, I present the observational difficulties and study the detectability of kilonovae using survey simulations. I quantify the effect of survey depth and choice of filters to optimize detection probability. I highlight the importance of accounting for the asymmetries expected for kilonovae (KNe). One conclusion of this licentiate thesis is that it is unlikely to detect a new KN under the same conditions as AT2017gfo. Even if the intrinsic properties were similar, the orientation of the KN would significantly affect the detection feasibility. 

We have performed several search campaigns for KN candidates within the Zwicky Transient Facility (ZTF),  the Global Relay of Observatories Watching Transients Happen (GROWTH) and the Electromagnetic counterparts of gravitational wave sources at the Very Large Telescope (ENGRAVE) collaborations. We can distinguish targeted searches after GW triggers and archival searches for serendipitous KN detections. Both kinds of investigations have so far failed to detect KNe with ZTF. Nevertheless, non-detection studies provided meaningful constraints on the luminosity function and the rates of KNe. 

Place, publisher, year, edition, pages
Stockholm University, 2022
Keywords
kilonovae - neutron stars - gravitational waves
National Category
Astronomy, Astrophysics and Cosmology
Research subject
High Energy Physics; Physics
Identifiers
urn:nbn:se:su:diva-200803 (URN)
Presentation
2022-02-04, Albano 3:6228 - Mega (house 3), Fysikum, Albanova universitetscentrum, Roslagstullsbacken 21, Stockholm, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council, 2016-06012
Available from: 2022-02-03 Created: 2022-01-12 Last updated: 2022-02-03Bibliographically approved
Andreoni, I., Coughlin, M. W., Almualla, M., Bellm, E. C., Bianco, F. B., Bulla, M., . . . Singer, L. P. (2022). Optimizing Cadences with Realistic Light-curve Filtering for Serendipitous Kilonova Discovery with Vera Rubin Observatory. Astrophysical Journal Supplement Series, 258(1), Article ID 5.
Open this publication in new window or tab >>Optimizing Cadences with Realistic Light-curve Filtering for Serendipitous Kilonova Discovery with Vera Rubin Observatory
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2022 (English)In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 258, no 1, article id 5Article in journal (Refereed) Published
Abstract [en]

Current and future optical and near-infrared wide-field surveys have the potential to find kilonovae, the optical and infrared counterparts to neutron star mergers, independently of gravitational-wave or high-energy gamma-ray burst triggers. The ability to discover fast and faint transients such as kilonovae largely depends on the area observed, the depth of those observations, the number of revisits per field in a given time frame, and the filters adopted by the survey; it also depends on the ability to perform rapid follow-up observations to confirm the nature of the transients. In this work, we assess kilonova detectability in existing simulations of the Legacy Survey of Space and Time strategy for the Vera C. Rubin Wide Fast Deep survey, with focus on comparing rolling to baseline cadences. Although currently available cadences can enable the detection of >300 kilonovae out to ∼1400 Mpc over the 10 year survey, we can expect only 3–32 kilonovae similar to GW170817 to be recognizable as fast-evolving transients. We also explore the detectability of kilonovae over the plausible parameter space, focusing on viewing angle and ejecta masses. We find that observations in redder izy bands are crucial for identification of nearby (within 300 Mpc) kilonovae that could be spectroscopically classified more easily than more distant sources. Rubin's potential for serendipitous kilonova discovery could be increased by gain of efficiency with the employment of individual 30 s exposures (as opposed to 2 × 15 s snap pairs), with the addition of red-band observations coupled with same-night observations in g or r bands, and possibly with further development of a new rolling-cadence strategy.

Keywords
Transient detection, Transient sources, Neutron stars, Gravitational wave sources, Surveys, Optical astronomy
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-200406 (URN)10.3847/1538-4365/ac3bae (DOI)000733000200001 ()
Available from: 2022-01-05 Created: 2022-01-05 Last updated: 2022-01-05Bibliographically approved
Andreoni, I., Margutti, R., Salafia, O. S., Parazin, B., Villar, V. A., Coughlin, M. W., . . . Tanvir, N. (2022). Target-of-opportunity Observations of Gravitational-wave Events with Vera C. Rubin Observatory. Astrophysical Journal Supplement Series, 260(1), Article ID 18.
Open this publication in new window or tab >>Target-of-opportunity Observations of Gravitational-wave Events with Vera C. Rubin Observatory
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2022 (English)In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 260, no 1, article id 18Article in journal (Refereed) Published
Abstract [en]

The discovery of the electromagnetic counterpart to the binary neutron star (NS) merger GW170817 has opened the era of gravitational-wave multimessenger astronomy. Rapid identification of the optical/infrared kilonova enabled a precise localization of the source, which paved the way to deep multiwavelength follow-up and its myriad of related science results. Fully exploiting this new territory of exploration requires the acquisition of electromagnetic data from samples of NS mergers and other gravitational-wave sources. After GW170817, the frontier is now to map the diversity of kilonova properties and provide more stringent constraints on the Hubble constant, and enable new tests of fundamental physics. The Vera C. Rubin Observatory's Legacy Survey of Space and Time can play a key role in this field in the 2020s, when an improved network of gravitational-wave detectors is expected to reach a sensitivity that will enable the discovery of a high rate of merger events involving NSs (∼tens per year) out to distances of several hundred megaparsecs. We design comprehensive target-of-opportunity observing strategies for follow-up of gravitational-wave triggers that will make the Rubin Observatory the premier instrument for discovery and early characterization of NS and other compact-object mergers, and yet unknown classes of gravitational-wave events.

Keywords
Gravitational wave sources, Neutron stars, Black holes, Astronomical methods, Transient detection
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-205200 (URN)10.3847/1538-4365/ac617c (DOI)000794984400001 ()2-s2.0-85131351937 (Scopus ID)
Available from: 2022-06-09 Created: 2022-06-09 Last updated: 2022-11-15Bibliographically approved
Sagués Carracedo, A., Bulla, M., Feindt, U. & Goobar, A. (2021). Detectability of kilonovae in optical surveys: post-mortem examination of the LVC O3 run follow-up. Monthly notices of the Royal Astronomical Society, 504(1), 1294-1303
Open this publication in new window or tab >>Detectability of kilonovae in optical surveys: post-mortem examination of the LVC O3 run follow-up
2021 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 504, no 1, p. 1294-1303Article in journal (Refereed) Published
Abstract [en]

The detection of the binary neutron star (BNS) merger GW170817 and the associated electromagnetic (EM) counterpart, the ‘kilonova’ (kN) AT2017gfo, opened a new era in multimessenger astronomy. However, despite many efforts, it has been proven very difficult to find additional kNe, even though LIGO/Virgo has reported at least one BNS event during their latest run, O3. The focus of this work is the exploration of the sensitivity of the adopted optical surveys searching for kNe during O3. We propose ways to optimize the choices of filters and survey depth to boost the detection efficiency for these faint and fast-evolving transients in the future. In particular, we use kN models to explore the dependence on ejecta mass, geometry, viewing angle, wavelength coverage, and source distance. We find that the kN detection efficiency has a strong viewing-angle dependence, especially for filters blueward of i-band. This loss of sensitivity can be mitigated by early, deep, observations. Efficient gri counterpart searches for kNe at ∼200 Mpc would require reaching a limiting magnitude mlim = 23 mag, to ensure good sensitivity over a wide range of the model phase-space. We conclude that kN searches during O3 were generally too shallow to detect BNS optical counterparts, even under optimistic assumptions.

Keywords
gravitational waves, surveys, neutron star mergers
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-195755 (URN)10.1093/mnras/stab872 (DOI)000656137100092 ()2-s2.0-85107866088 (Scopus ID)
Available from: 2021-08-26 Created: 2021-08-26 Last updated: 2024-04-11Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-3498-2167

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